<!DOCTYPE html>

<html lang="zh">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js 基础知识3 </title>

</head>

<body>
    <div id="demo">
        这里是内容
    </div>
    <script src="main.js"></script>
</body>

</html>
